Transcript for Mark Zuckerberg Most Generous American Philanthropist in 2013

America's number one. FaceBook founder Mark Zuckerberg and his wife were the most generous American philanthropist last year they donated eighteen million FaceBook shares worth almost a billion dollars to us. Silicon Valley charity in December. Zuckerberg FaceBook page says his network is twenty feet. Billion dollars -- while drop in the bucket.

This transcript has been automatically generated and may not be 100% accurate.

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